Method and apparatus for saturating felt



Oct. 18, 1955 B. s. PENLEY METHOD AND APPARATUS FOR SATURATING FELT 4Sheets-Sheet l Filed June 3, 1952 MMTSIMME ATTORNEY.

Oct. 18, 1955 B. s. PENLEY 2,721,144

METHOD AND APPARATUS FOR SATURATING FELT Filed June 3, 1952 4Sheets-Sheet 2 INVENTOR.

BENJAMIN S. PENLEY ATTO R N EY.

Oct. 18, 1955 B. s. PENLEY 2,721,144

METHOD AND APPARATUS FOR SATURATING FELT Filed June 5, 1952 4Sheets-Sheet 3 \NVENTOR.

BENJAM N S. PEN L EY LZM ATTORNEY.

B. s. Pl-:NLEY 2,721,144

METHOD AND APPARATUS FOR SATURATING FELT Oct. 18, 1955 Filed June 5,1952 4 Sheets-Sheet 4 FIGA.

INVENTOR.

BENJAMIN S. PENLEY ATTORN EY.

United States Patent O 2,721,144 METHOD AND APPAIITEJS FOR SATURATINGBenjamin S. Penley, Birmingham, Ala., assignor to Allied Chemical & DyeCorporation, New York, N. Y., a

corporation of New York Application June 3, 1952, Serial No. 291,530 1i)Claims. (Cl. 117-47) This invention relates to saturating felt and moreparticularly refers to new and improved methods and apparatus forimpregnating felt with bituminous saturants such as asphalt, tar andpitch for use as roong, insulation, etc.

Dry felt employed in industry for purpose of saturating with a bitumenis a porous material containing a vast number of small voids andgenerally having a moisture content within about 3 to 6 percent ofmoisture. ln conventional commercial practice the felt is saturated byimmersion in a liquid body of hot saturant, e. g. hot asphalt at about475 F. As the hot asphalt penetrates into the sheet of felt it is cooledby the sheet and becomes viscous, so that further penetration is slow ortemporarily stopped. The heat of the asphalt converts the moisture inthe sheet to steam which together with entrapped air, must escape fromthe voids of the sheet before the sheet can be completely saturated withthe asphalt. When the surface layers on both sides of the sheet arefilled with asphalt which has become viscous because of the cooling bythe sheet, the escape of the steam and the entrapped air is graduallyslowed and does not proceed appreciably until suicient heat ows byconduction into the viscous asphalt to render it uid. Since both asphaltand felt are relatively poor conductors of heat this consumesappreciable time. Accordingly, conventional saturators have attainedconsiderable length in order to provide the necessary time element. ln amodification of the ordinary process only one side of the sheet isbrought into contact with the surface of the hot asphalt. The modifiedprocess shortens this time a little by permitting the steam andentrapped air to escape through that side of the sheet not in contactwith the hot asphalt. However, it still requires the time necessary toreheat the asphalt which has penetrated the surface layers of one sideof the sheet and have been cooled thereby.

it is known that the friction of the sheet of felt passing through thebody of saturant in a kettle creates a drag which varies as the squareof the speed of the sheet and which is proportional to mount ofimmersion, i. e. length of sheet in the kettle. This hydraulic dragcauses tension in the sheet and, when excessive, results in breaks inthe felt sheet. This tendency to break is further increased by prolongedimmersion which causes or tends to cause charring of the felt orotherwise weaken its structure. Approximately half of the total loss ofmachine time due to felt failures occurs in the saturator alone.

it has been suggested to preheat felt for the purpose of drying outmoisture therefrom by-(a) coating one side of the sheet with hotasphalt, the heat of which asphalt converts the moisture in the sheet tosteam which escapes from the unsaturated side of the sheet, and (b)passing the sheet of Afelt through hot rolls which conduct heat to thesheet converting the moisture therein to steam. While both these methodsdecrease the amount of moisture in the felt they are subject to severalinrmities. in method (a) the surface layer of asphalt on one side of thesheet prevents escape of moisture and air during complete saturation ofthe sheet until the surface layer becomes suiiiciently heated to be in aliuid condition thereby prolonging the time for saturation. In method(b), due to the insulating properties of the felt, incomplete moistureand air removal is effected unless extremely 2,721,144 Patented Oct. 18,1955 ice high temperatures and prolonged time are employed which mayresult in charring and deterioration of the felt.

Because of the inherent limitations of the commercial processes forsaturating felt due to entrapped air and moisture and long immersiontime required, it has been found impractical to employ saturants of highsoftening point, above about F. As a. result, shingles of desiredrigidity are not produced and, furthermore, the shingles produced in theconventional manner require additional processing steps to prevent themfrom bleedingj sliding or blistering Sliding is that defect in rootingwhich is evidenced by a gross slippage of the face coating from thesaturated felt. Blistering is that defect evidenced by an eruption ofvarious-sized vesicles within the coating or between the coating and thesaturated felt.

One object of the present invention is to provide methods and apparatusfor saturating felts at rates to reduce the time of immersion to a valueappreciably lower than hitherto obtained.

Another object of the present invention is to provide methods andapparatus minimizing hydraulic drag during saturation of felt therebysubstantially eliminating breaks during such saturation.

A further object of the present invention is to provide methods andapparatus for reducing the time of immersion of the felt in the saturantso that charring of felt will not occur.

A still further object of the present invention is to provide apparatusfor saturating felt which substantially completely encloses the saturantthereby reducing lire hazards to a Another object of the presentinvention is to provide improved methods and apparatus for theelimination of entrapped gases and water vapor from felt.

Another object of the present invention is to provide methods andapparatus for the saturation of felt with high softening point saturantsthereby providing desired rigidity of shingle stock by the saturationstep.

Further objects and advantages will be apparent from the followingdescription and accompanying drawings.

Referring to the drawings:

Figure l is a diagrammatic ow sheet illustrating the process of thepresent invention.

Figure 2 is an isometric View in partial section of the pressuresaturator.

Figure 3 is a front elevation in partial section of the pressuresaturator.

Figure 4 is a plan View of the grooved cylinder roll employed in thepressure saturator.

Figure 5 is an enlarged section of the grooved cylinder roll taken online 5 5 of Figure 4.

Figure 6 is an enlargement in section of a portion of the pressuresaturator to show in detail the construction of the saturator at thepoint of inlet of saturant and the position of the doctor blade.

Figure 7 is an isometric view in section of a portion of a shingle toillustrate its structure and composition.

Referring to Figure l, cold, moist felt 1 termed in industry as dry feltis continuously drawn through a preheater designated generally bynumeral 2 wherein the felt is preheated and moisture expelled therefrom.Preheater 2 is generally constructed of an outer shell 3, an innergrooved perforated rotating drum 4 and entrance and exit pressure rolls5 and 6. Sheet felt 1 passes between pressure roll 5 and drum 4 drivenby any suitable power means, as for example an electric motor not shownin the drawing, and then emerges from preheater 2 by passing betweenexit pressure roll 6 and drum 4. A hot gaseous fluid such as combustiongas, air or superheated steam, preferably at a temperature below 500 F.to avoid charring of the felt and under superatmospheric pressure, about3-10 p. s. i. gauge, or higher, is introduced through line 7 into shell3 maintained under superatmospheric pressure by means of suitable seals,not shown in the drawing. Hot combustion gas for preheating the felt maybe generated by forcing air and fuel through respective lines 8 and 9into furnace 11 wherein combustion takes place and the hot combustiongases then discharged through conduit 7. Control of the temperature ofthe combustion gases may be accomplished by one or a combination ofconventional methods such as passing the combustion gases from furnace11 in indirect heat exchange with a cooling medium, direct injection ofcold air into the hot combustion gases to temper them, or introducingexcess air into furnace 11.

The hot gases introduced through line 7 into preheater 2 in the spacebetween drum 4 and shell 3 can escape only by passing through the feltsheet 1 as it lies against drum 4 and then through perforations in drum4 into the interior of drum 4. The gases partially cooled by passagethrough the felt sheet then escape from the interior of the drum throughhub emaust conduit 12. A small portion of drum 4 intermediate pressurerolls 5 and 6 is not covered by the sheet of felt permitting a minoramount of the gases to pass through the perforations in the drum at thatpoint. Therefore, a covering 13 in the nature of a hood is disposedabove preheater 2 to collect the escaping gases and release them to theatmosphere through stack 14. The pressure of the hot gases enteringpreheater 2 holds sheet 1 tight against drum 4 and rotation of this drumprovides the necessary pull to carry the sheet through the preheaterwithout imposing undue stress on the sheet. The hot gases desirablyenter the preheater at temperatures up to the maximum permissiblewithout charring the felt.Y In the case of felt made from wood, paperand rag fibers, this temperature is about 500 F. but depends somewhat onthe speed at which the felt is passed through the preheater. Passage ofthe hot gases through the felt brings the source of heat into minutelyintimate contact with the individual fibers of the felt; the felt isheated rapidly, the moisture in the felt is converted to steam and thesteam and entrapped air are driven out of the felt so that the feltemerges from the preheater substantially bone dry and at a temperatureof 20 to 100 F. to below that of the entering top gases. Thistemperature can of course be varied by changespin velocity of the felt,quantity of hot gas per unit of felt, and size of the preheater. Thefelt leaving preheater 2 is at a state of dryness and temperature idealfor saturating with asphalt. Y

The construction and method of operation of the pre? heater is describedin greater detail in my cofiled application, Serial No. 291,529, tiledJune`3, 1952, entitled Felt Heater and Dryer.

The dry hot felt 1 pulled by rolls 15 and guided by roll 16 next passesthroughV loop 17 which is enclosed, not shown in the drawing, to avoidloss of heat. Loop 17 can be small in size--it need only be adequate topermit guiding and to provide sufficient slack in the sheet of felt soas to prevent tension and breakage of the felt during its passage fromthe heater to the pressure saturator.

The pressure saturator designated Y generally by numeral 18 isconstructed of a grooved imperforate cylinder roll 19 surrounded byshell 21, entrance pressure roll 22, exit pressure roll 23, and sealingmeans more clearly shown in Figure 2 as will be described later. The dryhot felt sheet passes between entrance pressure roll 22 and grooved roll19 driven by any suitable power means, around grooved drum 19, and thesaturated felt emerges from saturator 18 after passing between exitpressure roll 23 and grooved drum 19. Hot saturant at conventionaltemperatures, e. g. up to about 475 F., is introduced through lines 24,25 and valve 26 into the space between shell 21 and grooved drum 19.Within the pressure saturator felt sheet 1 is carried by roll 19 becausethe pressure of the hot saturant holds the sheet tight against groovedroll 19. Therefore, pull on the sheet is much less than in conventionaltype saturators. The hot saturant under superatmospheric pressureintroduced into the space between shell 21 and roll 19 can escape onlyby passing through the hot felt sheet 1 as it lies against roll 19 andthence along the circumferential grooves around the drum until the hotsaturant emerges at the top between pressure rolls 22 and 23 where roll19 is not covered by the felt sheet. Saturant accumulates at this pointuntil it overflows weir 27 and returns through pipe 28 to surge tank 29.Excess saturant is recirculated from the bottom of surge tank 29 throughline 31 and forced by pump 32 through lines 33 and 44 into saturantstorage tank 35. Pump 36 maintains suitable pressure on the hot saturantto force it through the felt sheet; this pressure is of the order ofl-lO p. s. i. gauge and varies according to thickness of the sheet,viscosity of the saturant as dictated by its softening point andtemperature, speed of the sheet and size of the equipment. The immersiontime to which the felt sheet is exposed to hot saturant in the pressuresaturator is of the order of l to 5 seconds; typical time is 11/2seconds. Immersion time in a conventional type saturator ranges from 45to 70 seconds. Since both the felt sheet and the saturant are hot thereis no appreciable cooling of the asphalt and no viscous layer is formedwith the attendant time required to reheat. The hot saturant enters andpasses through the felt sheet in one direction driving ahead of it hotgases entrapped in the sheet. Since all impediments to saturation havebeen removed or avoided, saturation proceeds uniformly, completely andvery rapidly.

In order to replenish the Yhot saturant consumed in saturator 18 andmaintain the temperature of the saturant therein, saturant from storagetank is withdrawn through line 34 from saturant storage tank 35, forcedby saturant pump 36 through line 37 and heat exchanger 38 wherein thesaturant is heated to desired operating temperatures under automaticcontrol, by indirect contact with a heating fluid, as for example hotoil, passing through coil 39, thence through lines 41, 24, 25 and valve26 into saturator 18. The saturant may be returned from surge tank 29 tosaturant storage tank 35 via lines 31, 33, 44 and valve 45. Valve 42,which may be operated manually or automatically, bleeds oi a portion ofthe saturant owing through line 24, directing it through line 43 intosurge tank 29, thereby controlling pressure in saturator 18. Valve 46 inline 24 may be partially opened to by-pass a portion of the saturantflowing through line 33. The foregoing saturant circulatory systemprovides a method of controlling the volume, temperature and pressure ofa continuous stream of hot saturant passing in contact with the felt.

In the process of the invention, the impregnating asphalt moves rstthrough the felt sheet from outer side of the supported sheet immersedin a body of asphalt toward the support, for example, rotating drum 19kof the preferred pressure saturator of the drawings. The hot asphaltemerged from the inner section of the sheet passes as a multiplicity ofseparate streams through the passageways or conduits dened by the innerunsupported portions of the sheet and by the channels occurring betweenadjacent areas or surfaces engaging the sheet, for example, lands 112(Figure 6), until disengaged from the sheet when the latter is removedfrom its support. Hence, in the process of the invention, the ow of hotasphalt described serves a threefold purpose. First it holds the sheetagainst its support, preventing undue stresses therein. Then it movesgenerally from the inner to the outer surfaces of the sheet, heating itand driving out air and moisture. Thereafter, the hot asphalt remains incontact with the inner surface to provide such additional heat andpenetrating eiect as may be needed to complete the saturation in veryshort or even minimum time, permitting preservation to maximum extent ofthe desired structural characteristics of the felt. Duration of contactof the streams of asphaltwith the inner sheet surface is a function ofporosity of the felt sheet and the vis- CQsity of the asphalt during andafter passage therethrough, as well as of the total immersion time ofthe sheet in the body of asphalt.

Threading, which is an important phase of the operation, is accomplishedby passing sheet 1 over guide 16, then over roll 22 employing guide 87(Fig. 3) to guide sheet 1 thereon, and then passing the sheet into thenip of roll 22 and drum 19, the initial stage of threading carried outin the absence of pressure. After sheet 1 has entered the nip, thepressure is turned on which holds sheet 1 against drum 19 while themachine is started and until the sheet reaches exit roll 23. To insurehigh velocity ow of saturant through the annulus formed by drum 19, andshell 40, the cross-sectional area of the annulus is desirably madesmall to provide a minimum clearance between sheet 1 and shell 49thereby aiding in maintaining more uniform pressure conditions duringthreading and saturation. Doctor blade 92 serves to guide sheet 1 ontodrum 19 during threading and prevent the sheet from continuing aroundroll 22. Exit sheet guide 99 serves to guide the sheet when threadinginto the nip of rolls 47 and 23.

Figure 2 is an isometric drawing of pressure saturator 18 showing itsconstruction in more detail. The felt sheet 1 or felt fabric or web, asit is sometimes referred to, enters pressure saturator 18 by passingbetween entrance pressure roll 22 and grooved cylinder roll 19, aroundgrooved cylinder roll 19 emerging by passing between exit pressure roll23 and cylinder 19, and then between squeeze roll or ringer roll 47 andexit pressure roll 23. The entire shell designated in Fig. 1 by numeral21 surrounding cylinder 19 is constructed of two sections, an upper half48 open at its top and a lower half 49. Hot saturant is introduced intopressure saturator 1S through conduit 25. The body of saturant in thepressure saturator is maintained under pressure by means of sealspressing against the sides and ends of pressure rolls 22 and 23. Theseal construction at the side of exit pressure roll 23 comprises a sealsupporting block 51 on which is disposed seals 52 which in turn are heldin place and urged against pressure roll 23 by means of springs onpusher bar 50, dogs 53 and vertical and horizontal seal pressure springs54. Corner seal 55 is retained in position by spring 56. The end ofpressure roll 23 is sealed by seal 57 which is retained in positionpressing against roll 23 by means of pusher bar 58 and springs 59. Asimilar sealing spring structure is provided on the opposite end ofpressure roll 23. Likewise, the seals on entrance pressure roll 22 aresimilar in construction to those described in connection with exitpressure roll 23. As will be seen from the drawing, pressure roll 22 isprovided with an entrance seal supporting block 61 on which is mountedpusher bar 62, dogs 63 and vertical and horizontal springs 64. Alsoshown is corner seal 65 with corresponding pusher bar 66 and spring 67,as well as end seal 68, pusher bar 69, dogs 71 and springs 72. As seenin the drawing a portion of grooved cylinder roll 19 extends above shell48. To prevent leakage at this point seal 73, pusher bar 74, dogs 75 andsprings 76 are provided.

Thus, saturant under pressure entering through conduit must pass throughfelt sheet 1, thence along the grooves in grooved cylinder 19 and escapefrom the top of grooved cylinder 19 at points intermediate pressurerolls 22 and 23. A saturant overilow pan 77 enclosed by walls 78, 79, 81and 82 collects the saturant after it has traversed the grooves in drum19. Any slight leakage of saturant through the seals surroundingpressure rolls 22, 23 and cylinder 19 also collects in pan 77. Pan 77 isdivided into two sections by means of a Weir composed of stationary Weirbar 83 an-d movable Weir gate 84 whichv latter permtis adjustment of theheight of the Weir. Two drain or dump gates 85 are incorporated in theweir to by-pass the weir, if desired, particularly when draining thesystem of saturant. In operation the level of saturant is permitted tobuild up to'a height above the uppermost portion of grooved cylinder 19thereby acting in the nature of a hydraulic seal. EX- cess saturantoverflows Weir gate 84 and then drains through saturant drain pipes 28to surge tank 29 shown in Figure 1. Cylinder 19 is rotated by powermeans not shown in the drawing connected to shaft 86 provided with asuitable stuiiing box and extending from shell 48, 49.

Referring to Figure 3 sheet 1 passes over guide 16, thence guided byentrance guide sheet 87 onto pressure roll 22 and between pressure roll22 and grooved cylinder roll 19. Deckle plate 88 held in position bysupport 89 extends to the edge of sheet 1. In the upper part of shell 4Sis provided a small chamber 91 for the introduction of saturant throughconduit 25 and to provide space for the installation of doctor blade 92supported by spring mountings 93 to urge the doctor blade againstentrance pressure roll 22. Figure 3 also shows a section of the sealspressing against roll 22 which seal arrangement rests on iloor 94 ofoverllow pan 77 which floor is also the ceiling for chamber 91. Theentrance seal constitutes seal supporting block 61, entrance roll seal65, dogs 63, pusher bar 62 and pressure springs 64. As grooved cylinder19 is rotated by power means driving shaft 86, web 1 clings to cylinder19 and exits by passing between exit pressure roll 23, thence betweensqueeze roll 47 and exit pressure roll 23 and nally along wiper rolls104 resting on wiper roll support 96. Extension of shaft 86 carries alarge gear not shown in the drawing, which is driven by a pinion, notshown, the latter being powered by conventional means such as anelectric motor or a pulley. The above large gear meshes with pinions,not shown, on the extended shafts of rolls 22 and 23 which actuatesthese rolls. On the extended shaft of roll 23 there is also a sprocket,not shown, which through chain 128 drives sprocket 127 that is mountedon the extended shaft on wiper roll 125. Also on the extended shaft ofroll is gear 126 meshing with another gear of the same number that ismounted on the extended shaft of roll 104 to drive this roll. Exitdeckle 97, support 98 for the exit deckle, and exit sheet guide 99similar to entrance deckle 88, support 89 and entrance guide sheet 87are disposed adjacent exit pressure roll 23. Deckles 88 and 97 are usedto blank oit" rolls 22 and 23 beyond the edge of sheet 1. These decklesmay be substituted for other deckles of different width to permitoperation with sheets of varying Widths. The structural support forinlet pressure roll 22 is indicated by numeral 101; and the exitpressure roll 23 and squeeze roll 47 structural support is showngenerally by numeral 102.

Saturant overilow pan 77 is divided by weir 27 composed of stationaryweir bar 83 and movable weir gate 84. Plate 103 extending at an anglefrom overflow pan 77 and beneath wiper rolls 104 collects excesssaturant removed by the wiper rolls which saturant drains down plate 103into overflow pan 77. Overflow saturant ows down through drainpipes 28into surge tank 29. Shell 49 may be provided with clean-out plates 105to permit access to the interior of shell 49 primarily for the purposeof cleaning it at the end of the run. Also at the end of the run allsaturant may be removed from the interior of shell 49 through drainpipe106. Pressure is maintained on entrance pressure roll 22 and exitpressure roll 23 by means of spring loaded rods designated generally bynumeral 107. Vertical adjustment of pressure on pressure rolls 22 and 23for the purpose of adjusting the space for paper thickness betweenpressure rolls 22 and 23 and grooved cylinder roll 19 is accomplished bymanipulating wheel 108 connected by conventional gears to rods 107. Theusual structural elements designated by numeral 109 support the entiresaturator structure.

Figure 4 is a plan view of grooved cylinder roll 19 showing shafts 86extending therefrom. As will be noted a plurality of adjacent parallelflow grooves 111 extend around cylinder 19.

One important advantage in employing an imperforate 7 grooved drum asillustrated in Figures 4 and 5 is that varying widths of web may beaccommodated in the apparatus without change in structure or operationexcept for the slight mechanical change required in changing thedeckles. `Of importance, when saturating a sheet supported by a drumhaving circumferential grooves is the fact that the entire sheetincluding particularly the edges is fully saturated by Saturant underpressure. The grooved drum 19 as illustrated in Figures 4 and 5 also hasthe advantage of having a minimum land area, i. e., surface which is inphysical contact with the felt resting on the grooved drum 19. This landarea is designated by numeral 112 (Figure 5) and as previously mentionedhas a width of about V32, Whereas the open area represented by numeral111 has a width of about fief-thus the land area represents about 25% ofthe total area. It is important to have the land area as small aspossible in that it permits greater exposure of the'felt to Saturantpassing therethrough and, consequently, more rapid and uniformsaturation of the felt. Furthermore, it will be noted that the land areaof the grooved drums are in the form of very narrow (1/32) strips withSaturant flowing through on each side of the strips which Saturant, asfound in practice, readily permeates the felt resting on the strips ofland area. In contrast, were a perforated drum employed the holes in thedrum could not in practical operation-be greater than 1A diameter orelse the felt would push Vthrough the perforations with distortion anddisruption of the felt. In a perforated drum having 1A holes the landarea is approximately 2/3 of the total area, and this land area also hasnumerous points between the holes of relatively large size in contactwith the drum through which it is diflicult to pass Saturant through thefelt with the result that longer time is required and less uniformsaturation of the felt is accomplished.

Figure is an enlargement of a portion of Figure 4 to show more clearlythe nature of flow grooves 111. Desirably, the flow grooves 111 areconstructed to have an opening of about 2%,2", a depth of about 1A" anda land area, as indicated by numeral 112, of 1/32. The overalldimensions of grooved cylinder 19 may be about 3 feet in diameter andabout 4 feet or more long.

Figure 6 is an enlargement of a portion of the saturator showing in moredetail the position of the doctor blade and the chamber into whichSaturant is introduced. Hot Saturant is pumped under pressure throughinlet 25 into chamber 91 flowing through web 1 carried on groovedcylinder roll 19. Above cylinder 19 is entrance pressure roll 22 againstwhich doctor blade 92 presses. To the left of entrance pressure roll 22is shown entrance seal supporting block 61 resting on the ceiling 94 ofchamber 91 which also acts as a floor for overiiow pan 77. As seen inFigure 6 doctor blade 92 is mounted and adjusted by means of bolts 93,one of which is provided with a spring 113 to urge doctor blade 92against pressure roll 22.

Ordinarily, threading the pressure saturator is a difcult task. In thepresent construction, as illustrated by Figures 3 and 6, threading thepressure saturator is quite simple. This is accomplished at the start ofthe operation by first placing the end of Web 1 along pressure roll 22until the end of felt 1 extends a short distance beyond the bite betweencylinder 19 and pressure roll 22. Saturant under pressure is thenintroduced through inlet 25. Cylinder 19 is rotated slightlycounter-clock wise. The Saturant under pressure in chamber 91 pushesagainst the outer surface of felt 1 causing it to cling to cylinder 19.Doctor blade 92 and curved wall 114, which is an extension of uppershell 48, guide the felt 1 along cylinder 19 and prevent it fromstraying off cylinder 19. Since the hot Saturant under pressure fillsthe annulus between cylinder 19 and shell 48, 49, the pressure of theSaturant causes the felt to cling to cylinder 19 during the entiretravel of felt 1 along cylinder 19 with theY result "8 that during thethreading of felt 1 and subsequent travel of felt 1 along cylinder 19,the passage of web 1 along cylinder 19 continues without any diliiculty.

In conventional saturators dry felt of 52 gauge can not be saturatedsatisfactorily with asphalt at felt speeds much in excess of 250-300lineal feet per minute. In the practice of the present inventionemploying the preheater and pressure saturator described above, feltspeeds of 360-400 lineal feet per minute were attained with satisfactoryresults. The open surface area of asphalt in conventional saturators hasa length of 20 feet or more. This open surface of hot asphalt is asource of fire hazard. The length ofasphalt surface in the pressuresaturator of the present invention is only 3 to 4 feet.

In the conventional method of producing shingles, felt of about 50-52gauge (51 gauge is equal to felt of 0.056) is pulled through a vat ofmelted asphalt. From long experience it has been found impractical toemploy asphalt having a softening point higher than 13S-140 F. as theSaturant because if higher melting point asphalts were employed .thetime required for saturating felt would be too long and the hydraulicdrag would be too great. The resultant felt saturated with the 13S-140F. softening point asphalt is quite flexible and its surface sticky. Oneside of the saturated asphalt, and for con, venience this side will betermed bottom side, is coated with a thin layer of a high softeningpoint asphalt of the order of 20D-240 F. softening point. This coatingtermed seal coat is covered with talc or mica to pre-Y vent sticking.The opposite side of the felt, i. e., the upper surface of the saturatedfelt, is covered with a relatively heavy layer of asphalt of about20G-240 F. softening point. This upper layer, top coating, of highsoftening point asphalt is then covered with a layer of granules orcrushed'slate and is the surface exposed to the weather when used asshingles. The use of high softening point asphalts, i. e. in excess of200 F. softening point, is undesirable in that such asphalts uponexposure to the atmosphere oxidize and become brittle. Nevertheless, theindustry had found it impractical to employ lower melting point asphaltsas top coating because at the point of contact between the top surfaceof the felt saturated with 13S-140 F. softening point asphalt and thebottom surface of the top coatingV there is a tendency for the topcoating to detach itself from the top surface of the saturated asphaltunless the top coating has a softening point in excess of 200 F.Furthermore, and perhaps more important, the finished shinglescontaining a Saturant of 13S-140 F. softening point asphalt lacksufficient rigidity, and in strong winds tend to blow up or ap on aVroof or similar structure which they cover, which action causes leaks.

In practice of my invention I have found that conventional felt employedfor the production of shingles can be saturated with 175-185 F.softening point asphalt to produce a shingle having improved rigidity.Furthermore, I have found it unnecessary to employ a top coating asphalthaving a melting point in excess of 200 F. and instead may employ a topcoating of asphalt having a softening point below 200 F., preferably175185 F. thereby increasing the life of the shingle when exposed to theatmosphere. When the top coating and the asphalt employed for use asSaturant have substantially the same softening point (ll85 F.) a firmbond is formed between the top coating and the saturated felt and thediculty of the top layer detaching itself from the saturated felt isobviated.

Further, the use of -185 F. softening point asphalt for saturating thefelt permits the elimination ofa seal coat required when lower meltingpoint asphalts are employed for saturating felt in the production ofshingles. All that is necessary when employing the 175-185 F. softeningpoint asphalt for saturating felt is simply coating the lower surfacewith talc or mica to prevent .stick- 9 ing. Thus, the practice of myinvention permits the production of improved shingles having longer lifeand greater rigidity at lower cost.

Figure 7 is a cross section of a shingle illustrating its compositionand structure. The inner layer 116 of the shingle is composed of felt ofabout 0.056" thickness saturated with asphalt having a softening pointof 175-185" F. Top coating 117 is about 0.060 thickness and consists ofasphalt having a softening point of about 175-190 F. The surface of topcoating 117 is covered with a layer of granules 118. Beneath thesaturated felt 116 is a thin layer of seal coat 119 of about .003- .005"thickness consisting of asphalt having a softening point of 175-190 F.The seal coat is covered with a layer 121 of talc or mica or othermaterial to prevent sticking. lf desired, seal coat 119 may be omittedand the bottom surface of the saturated felt 116 directly covered withtalc or mica 121. Shingles produced vvith 175-185 F. softening pointasphalt in accordance with the present invention have greater rigidityand do not deteriorate as rapidly as conventional shingles formed bysaturating felt with 13S-140 F. softening point asphalt.

When saturating felt with high melting point asphalt, e. g., l70185 F.softening point asphalt, it is highly desirable to iirst treat the feltin preheater 2, Figure 1, to facilitate the saturation of the felt. Theuse of the preheater while benecial is not necessary when impregnatingfelts with low melting point saturants.

Although certain preferred embodiments of the invention have beendisclosed for purpose of illustration it will be evident that variouschanges and modifications may be made therein without departing from thescope and spirit of the invention.

I claim:

1. A continuous method for saturating felt which comprises continuouslypassing hot gas under pressure against one surface and through acontinuously moving sheet of felt thereby heating and expellingentrapped moisture from the felt, continuously passing the thus heateddry felt around an imperforate circumferentially grooved rotatingcylinder, continuously passing hot liquid bituminous saturant undersuperatmospheric pressure against the outer surface of the felt sheetlying against the grooved cylinder and through the felt and into thegrooves of the cylinder thereby expelling entrapped gases from the feltand replacing it with saturant, continuously releasing excess saturantpassing through the felt via the channels formed by the grooves into anoverflow pan having walls surrounding the top of the imperforate groovedcylinder to receive and collect the released saturant, and continuouslywithdrawing the saturated felt sheet from the imperforate groovedcylinder.

2. A process for saturating felt which comprises passing a felt sheetthrough an annulus formed by an inner imperforate circumferentiallygrooved rotating cylinder` and an. outer shell surrounding all but thetop of the imperforate grooved cylinder with seals provided to maintainpressure on said annulus, introducing hot liquid bituminous saturantunder pressure through the outer shell into the annulus against theouter surface of the felt sheet around the grooved cylinder therebyexpelling entrapped gases from the felt and forcing the saturant throughthe felt sheet into the grooves lying on the inner surface of the feltsheet, and releasing excess saturant passing through the felt sheet intothe grooves at the top of the imperforate grooved cylinder into anoverow pan having walls surrounding the top of the imperforate groovedcylinder to receive and collect the released saturant.

3. Apparatus for saturating felt comprising in combination, animperforate circumferentially grooved rotating cylinder, a shellsurrounding all but the topmost portion of the grooved imperforatecylinder, an inlet and an exit pressure roll disposed above on each sideof the grooved cylinder immediately adjacent thereto, each said pressureroll being spaced from the grooved cylinder by about the thickness ofthe felt to permit the passage ci' felt between each pressure roll andthe grooved cylinder, seals surrounding the outer sides and ends of thepressure rolls and the up -er exposed ends of the grooved cylinderadapted to maintain pressure on the liquid bituminous saturantintroduced into the space between the grooved imperforate cylinder andthe surrounding shell, and an overow pan having walls surrounding thepressure rolls and seals at the top of the outer shell adapted toreceive and collect excess liquid bituminous saturant escaping from thegrooves or" the grooved cylinder at a point between the two pressurerolls.

4. Apparatus as claimed in claim 3 including a doctor blade adjacent theinlet pressure roll adapted to guide felt sheet from the inlet pressureroll onto the imperforate grooved cylinder.

5. Apparatus as claimed in claim 3 wherein said shell surrounding saidimperforate grooved cylinder is disposed to form an annulus of smallcross-sectional area to insure high velocity ow of saturant through theannulus.

6. Apparatus as claimed in claim 3 including an entrance sheet guideadjacent the inlet pressure roll adapted to guide felt sheet into thenip of the inlet pressure roll and the imperforate grooved cylinder, asqueeze roll adjacent the exit pressure roll, and an exit sheet guideadjacent the exit pressure roll adapted to guide felt sheet into the nipof the exit pressure roll and the squeeze roll.

7. Apparatus as claimed in claim 3 including a conduit for drainingsaturant from the overflow pan, a tank into which saturant from theconduit ows and means for returning saturant from the tank to the spacebetween the imperforate grooved drum and outer shell.

8. Apparatus as claimed in claim 3 including a weir partitioning theoverow pan and adapted to control the height of saturant liquid in theoveriow pan covering the exposed upper portion of the grooved cylinder.

9. Apparatus as claimed in claim 3 wherein the grooves in theimperforate cylinder have openings of about 329,2 width and the ridgesof the grooves have a width of about 1/32".

10. In saturating felt sheet with bituminous saturant, the processcomprising applying one side of the sheet to a support providing amultiplicity of raised spaced-apart surfaces having channelstherebetween, forcing liquid bituminous saturant under superatmosphericpressure through said sheet from the unsupported side thereof to presssaid sheet against said surfaces and to bridge said channels, andconducting excess liquid bituminous saturant emerged from the supportedside of said sheet as a multiplicity of streams along and in directcontact with said last named side through the conduits deiined by saidsheet and channels.

References Cited in the le of this patent UNITED STATES PATENTS 263,668Stelwagon Aug. 28, 1882 925,263 Ayrault June 15, 1909 1,109,819 BuhlSept. 8, 1914 1,268,430 Cady iune 4, 1918 1,275,216 Cady Aug. 13, 19181,714,206 Black et' al May 21, 1929 1,736,633 Schutte Nov. 19, 19291,831,630 Manker Nov. 10, 1931 1,842,111 Pater Jan. 19, 1932 1,845,775Zavertnik et al Feb. 16, 1932 1,942,383 Dickhaut et al Ian. 2, 19342,040,514 Dillon May 12, 1936 2,040,529 Pearl May 12, 1936 2,083,731Miller June 15, 1937 2,117,355 Pearl May 17, 1938 2,176,835 Cumfer Oct.17, 1939 2,206,915 Ochs July 9, 1940 2,326,723 Fasold et al Aug. 10,1943 2,400,681 Bristol May 21, 1946

1. A CONTINUOUS METHOD FOR SATURATING FELT WHICH COMPRISES CONTINUOUSLYPASSING HOT GAS UNDER PRESSURE AGAINST ONE SURFACE AND THROUGH ACONTINUOUSLY MOVING SHEET OF FELT THEREBY HEATING AND EXPELLINGENTRAPPED MOSITURE FROM THE FELT, CONTINUOUSLY PASSING THE THUS HEATEDDRY FELT AROUND AN IMPERFORATE CIRCUMFERENTIALLY GROOVED ROTATINGCYLINDER, CONTINUOUSLY PASSING HOT LIQUID BITUMINOUS SATURANT UNDERSUPERATMOSPHERIC PRESSURE AGAINST THE OUTER SURFACE OF THE FELT SHEETLYING AGAINST THE GROOVED CYLINDER AND THROUGH THE FELT AND INTO THEGROOVES OF THE CYLINDER THEREBY EXPELLING ENTRAPPED GASES FROM THE FELTAND REPLACING IT WITH SATURANT, CONTINUOUSLY RELEASING EXCESS SATURANTPASSING THROUGH THE FELT VIA THE CHANNELS FORMED BY THE GROOVES INTO ANOVERFLOW PAN HAVING WALLS SURROUNDING THE TOP OF THE IMPERFORATE GROOVEDCYLINDER TO RECEIVE AND COLLECT THE RELEASED SATURANT, AND CONTINUOUSLYWITHDRAWING THE SATURATED FELT SHEET FROM THE IMPERFORATE GROOVEDCYLINDER.